Radio receiving system



Jan. 21, 1930. J. s. KORANY RADIO RECEIVING SYSTEM Filed July 23. 1925 W jNVE TOR BY M7 ATTORNEYS.

Patented Jan. 21, 1930 v UNITED STATES PATENT OFFICE JULIUS S. KORANY, OF NEWARK, NEW' JElR EY, ASSIGNOR 01E ONE-HALF 'IO FREDERICK BACI-IMAN, OF EAST ORANGE, NEW JERSEY RADIO RECEIVING SYSTEM:

Application filed July 23,

My invention relates to radio receiving systems. The principal object of the invention is to provide a system of that class which is sensitive, which will amplify to a high 5 degree the waves received, and which will be highly selective for currents of any particular frequency for which it is tuned, all without producing objection able sustained oscillations.

It has heretofore been possible to secure sensitivity in a radio receiving system including a detector by causing the output or plate circuit to act inductively on the receiving or grid circuit, but the resultant system produced oscillations which are very objectionable for radio telephony. In my improved system I maintain the sensitivity of such old system while preventing the objectionable oscillations.

Other objects of the invention will appear more fully in the following detailed description and appended claim.

The accompanying drawing forming a part of this specification illustrates diagrammati- 5 cally one embodiment of my invention.

Referring to the drawing, the receiving system includes an electron detector tube 1 having the usual grid 2, filament 8 and plate 4. The grid circuit includes in addition to the grid 2, the filament 3, inductance 5, the variable inductively wound resistance 6 and blocking condenser 13. A variable condenser 7 is connected directly across the grid circuit to permit the tuning of the circuit to the frequency of the waves it is desired to receive. The filament circuit includes a source of current, such as the usual battery 8, to effect the heating of the filament. The circuit includ ing the plate 4 also includes a source of current, such as the usual battery 9, the primary of the trai'isformer 10, inductance 11, and the variable inductively wound resistance 6. Condenser 12 is connected across the battery 9 and the primary of transformer 10, as is usual, to separate the radio frequency and audio frequency components of the currents in the plate circuit by affording a bypass for the radio frequency oscillations. The secondary of the transformer 10 is in a circuit including the grid 14 and filament 15 of the 1925. Serial N0. 45,451.

usual amplifying electron tube 16. The filament 15 is heated by a suitable source of current, such as the battery 17. The plate 18 of the amplifier 16 is in circuit with the telephone receiver 19, the battery or other source of current 20, and the amplifier filament 15. The circuit shown accordingly has one stage of audio frequency amplification.

Inductances 11 and 5 are so coupled that the current in the circuit including coil 11, that is the detector plate circuit, induces voltage variations in the detector grid circuit with the result that there is a tendency of the system to produce sustained oscillations. I have shownthe coils 11 and 5 as arranged coaxial with each other and wound in the same direction, and structurally as a single coil, but the same effect may be produced by other arrangements, as will appear to those skilled in the art. To overcome this tendency to oscillation, I diminish the periodic inducing action of the coil 11 on the coil 5, as by the counter or damping inductance 21 suitably coupled with the inductance 11. The inductance 21 which is wound in a, direction opposite the inductance 11 is, as shown, connected across the detector plate circuit, so as to be in series with the coi of the inductively wound resistance 6.

While the inductance 21 is shown superposed coaxially on the inductance 11, it may be arranged in any other suitable way to produce the desired diminution in the periodic inducing action of the detector plate circuit on the detector grid circuit.

The variable inductively wound resistance (5 permits, through shifting of the contact 6, variation of the inductance and resistance in the detector grid and plate circuit so as to better adapt the system for the reception of waves of a wide range of frequencies.

The system is preferably designed so as to be on the verge of oscillation without being adjustable to produce the objectionable sus tained oscillations referred to. It has been found to be very sensitive and selective for waves of a wide range of frequencies, and to produce a high degree of amplification.

I prefer to use a loose inductive coupling between. the inductance 5 in the detector grid circuit and the inductance 22 of the antenna 23 to enable the system to operate uniformly over a wide range of wave frequencies. The antenna inductance is desirably formed of two equal coils or inductances 24 and 25 electrically connected to each other and the antenna and arranged so that the inductive effect of one opposes that of the other to the desired extent, but not completely. I have obtained good results by arranging the coils 24 and 25 at a fixed angle, preferably about 45, to each other. The coils 24 and 25 are, as shown, arranged at an angle to the inductance 5. This angle may be varied to obtain the desired coupling according to the length of the antenna.

My invention is not limited to the specific system shown but may be modified within the scope of the appended claim.

Having described my invention, what I claim as new and desire to protect by Letters Patent of the United States is 2- In a radio receiving system, the combination of a thermionic device, an inductance in the input circuit thereof, an inductance in the output circuit thereof and coupled to said first inductance, a third inductance wound upon said second inductance and in an opposite direction to the windings thereof and connected in the output circuit in shunt with said second inductance, and an antenna circuit including an inductance loosely coupled to the inductance in the input circuit of said device, the coupling inductance of the antenna including a plurality of coils electrically connected to each other and arranged to inductively oppose each other.

In testimony whereof, I have signed my name to this specification.

JULIUS S. KORANY. 

